Will snow hurt your garden this winter? Here’s what you should know

It's winter in Iowa and that means snow - and sometimes lots of it.

Gardeners sometimes worry that snow is bad for their plants, but in many cases, it actually helps protect them.

Snow is often called 'white mulch.” That's because when it covers plants, like a big fluffy white comforter, it protects them from temperature extremes and desiccating winds.

Snow also insulates the ground itself, preventing it from the extremes of warm and cold that can cause frost-heave, which can unearth plants and expose their vulnerable roots to bitter cold.

So when you are shoveling show, don't worry if you are tossing it on your perennials, roses, and other low-lying plants. As long as it doesn't contain salt, it's actually beneficial.

Remember, too, that snow is moisture. It eventually melts and is absorbed, at least partly, into the soil.

Of course, heavy, wet snow can be a problem for some plants, primarily evergreens. Extremely heavy snow load can snap branches and flatten smaller, more delicate evergreens. Usually, it's best to let nature do its thing. If there's a snowstorm and your favorite evergreens are bending over or branches seem to be straining, it's OK to gently brush off the snow or shake the branch gently. Just be careful not to do additional damage.

If ice is the culprit, that's another matter. Leave it and the plant alone. You're as likely to do additional damage as you are to help the plant in any significant way.

Will salt or de-icer hurt plants and soil?

When tending your driveways and walks after a snow, be careful about salt. Not only does it do damage to vehicles and concrete, it can also seep into the soil and damage plants, causing them in spring to grow unhealthy and often with a sickly yellow hue.

If possible, use more chemically friendly materials to make sidewalks and drives less slippery, such as coarse sand, sawdust or Kitty Litter.

If you must use salt, look for formulations that are less damaging to plants. Start by reading the label carefully. Many will state if they are less harmful to plants.

It's also helpful if you can avoid de-icer in the late winter through early spring, when plants are coming out of dormancy and are most vulnerable to salt damage.

Avoid those made with sodium chloride, also known as rock salt and one of the less expensive de-icers. Another de-icer, calcium chloride, is less harmful to plants than sodium chloride. Magnesium chloride is a less harmful option still.

Another good option is potassium chloride, also called muriate of potash. It's used in fertilizers and does minimal damage to plants. The best option of all is calcium magnesium acetate. It is, predictably, also the most expensive.

Whatever de-icer you use, follow any directions the label to determine recommended application methods and rates. Then use it as sparingly as possible.

If you have lawn or plants along a road, they likely will be subject to salt spray spread by city and county trucks. Or the salt is spread on the road, but with the next pass of the snow plow, it's thrown up onto your lawn and plantings.

Salt can damage plants fairly quickly. In late winter if it makes contact with buds and small twigs of some plants, it enters the plant cells or the spaces between the cells and makes them vulnerable to die back from freezing.

Salt in the soil holds onto moisture and doesn't make it available to plant roots, causing drought-like conditions for plants even though there might be ample rain and watering.

Another problem is that as the de-icer dissolves, it can create a substance that is toxic to plants, causing leaf scorch and its characteristic yellowing and browning of leaves.

Come spring, many gardeners worry when snow dusts their beautiful early-blooming bulbs, such as crocuses, daffodils, and early tulips. They're made for early spring and cold weather, and unless they're snapped by an ice storm, they will be fine.

Veronica Lorson Fowler is co-publisher of The Iowa Gardener website at theiowagardener.com.